Analysis And Research Of New Random Multiple Access Protocol In Wireless Ad Hoc Network

Ad Hoc network still has the ability to transmit information under harsh channel conditions,and plays an important role in military,civil and commercial applications.Ad Hoc network is composed of many distributed running nodes,which can join or quit at will,and make the network self-organized.However,due to the bad characteristics of short lifetime,improving the transmission efficiency of nodes has become the top priority.Access Media Access Control(MAC)in Ad hoc networks has an important impact on the overall system throughput rate and other performance indicators.As a key research direction,one of the key technologies of MAC protocol is CSMA protocol which evolved from ALOHA protocol.With the increasingly frequent application of wireless Ad Hoc networks and the popularization of information technology,a large number of information packets sent in the channel will inevitably lead to a significant increase in the probability of collision of information packets in the channel.This paper mainly carries out the following research work:Considering that the collision time slot length(hereinafter referred to as collision length)is too long to cause poor performance of the system,in order to reduce the channel occupation time,this paper proposes a three-clock non-persistent CSMA based on the variable collision length(N-CSMA).On this basis,multi-priority mechanism and three-time handshake mechanism with monitoring function are added.The multi-priority N-CSMA protocol and the N-CSMA protocol of three-time handshake mechanism with monitoring function are obtained.The mathematical expressions of key indicators such as throughput rate are derived by means of the average cycle method,and the theoretical deduction is confirmed by simulation experiments.When the collision length is small,the performance of these three protocols is greatly improved compared with the traditional two-clock non-persistent CSMA protocol.Because the N-CSMA protocol adopts the full probability transmission mode,it is impossible to reasonably control the number of information packets arriving in the channel according to the arrival rate.This paper proposes an improved CSMA protocol based on N-CSMA protocol:three-clock non-persistent P-CSMA with variable collision length(NP-CSMA).On this basis,adaptive mechanism,multi-priority mechanism and three-time handshake mechanism with monitoring function are added.NP-CSMA protocol with adaptive function,multi-priority NP-CSMA protocol,multi-priority NP-CSMA protocol with adaptive function and multi-priority NP-CSMA protocol of three-time handshake mechanism with self-adaptive function and monitoring function are obtained.When the collision length is small,the performance of these five protocols is greatly improved compared with the traditional two-clock P-CSMA protocol.In this paper,the average period method is used to deduce the above protocol theoretically.We also verify the correctness of the theoretical analysis by simulation experiments.Compared with traditional protocols,it is clear that these protocols have better performance.Different protocols can be selected according to different needs to meet people's needs.